Air log



April 6, 1943. E. v. RIPPINGILLE 2,316,021

` AIR LoG Filed Aug. 8, 1941 "IIS,

Bu 4 MEV;- Gttornegs Stwentor u Patented Apr. 6, 1943 VfRippingille,DetroitfMich., assignor to A,(reneral- Motors Corporation, Detroit,Mich., a

corporation of Delaware ll'AipliatimiAugust s, 1941, seria1No.4os,o`15

., 4 Claims.

This invention relatesto i'devices having an impeller .which is drivenby lluid flow.

It relates especially to uid flow meters, distance logs or odometers andthe like, in lwhich the speed at which the impeller is driven is used asa measure of the rate of fluid flow.

More specifically, it relates to impeller blades in air logs formeasuring the distance which.

an object traverses relatively to the air.

Such instruments are desirably small and lightly constructed, -withimpeller blades which are conveniently sheet steel stampings.

While such instruments can be produced within reasonable tolerancelimits, the blades particularly are too fragile to permit manufactureand assembly Within sufliciently close limits to insure duplication ofperformance characteristics of the assembly, and some means ofadjustment for accuracy is necessary.

The object of the invention is a means of adjusting the performance ofsuch a device to a given standard.

A more specific object of the invention is a means of adjusting thepitch of the impeller so that the instrument will conform to the desiredstandard of response.

The above and other objects of the invention will be apparent as thedescription proceeds.

According to the invention, screw means are provided for adjusting thepitch of the impeller yblade by bending deflection of its hub portion ina direction longitudinally of its supporting shaft, in a Iplanecontaining the shaft axis and normal to the center line of the impellerblade.

The drawing shows the application of the invention to an air log formeasuring the distance traversed by an airplane relatively to theambient a1r.

In the drawing:

Figure 1 is a View of the device in part-sectional elevation.

Figure 2 is a View on line 2 2 of Figure 1.

Figure :3 is a view on line 3-3 of Figure l.

Figure 4 is a sectional view on line 4-4 of Figure 1.

Figure 5 is an enlarged View of part of Figure 4 showing the manner inwhich the pitch off the impeller blade is adjusted by bending deflectionof its hub portion.

The impeller blade I has a hub portion 2, secured to a hub l3, on ashaft 4 which has end pivots supported in adjustable jewel bearings 5and l6 in a housing 1 and a housing 8 respectively, which are connectedtogether by a U- shaped .portion lo whichwin not interfere with turningof the impeller blade.

That portion of the shaft 4 within the housing 1 is provided with a wormI2, engaging a worm Wheel I4, on a cross shaft I5, on which there is acam I6 which lifts the spring arm Il of a point I8 of a conta-ct breakeraway from a stationary point I9 thereof, once for a definite number ofrevolutions of the shaft 4.

The points I8 and I9 of the contact breaker are arranged to make andbreak an electrical circuit through an electromagnetic counter (notshown), and since the number of revolutions of the shaft 4 isproportionate to the rate of air flow driving the impeller, the distancetraversed relatively to the air by an airplane on which the air log maybe mounted will be indicated by the counter reading, provided theinstrument is properly calibrated. Calibration can be effected bycomparison and adjustment of the device to a known standard in a windtunnel or in any other suitable way.

As shown, the instrument is provided with only one impeller blade, andits circular hub portion 2 is secured to the hub 3 by two rivets 22 and23, at spaced points along a line parallel to and removed from thecenter line of the impeller blade on one side of aplane -b containingthe shaft axis and the center line of the impeller blade, as shown mostclearly in Figure 2.

The hub 3 is chamfered at 25 and scooped away at 26 to remove weight tobalance the rotor assembly about the shaft axis in the manner shown bestin Figures 1 and 3.

A screw 28 is in screw threaded engagement with the hub 3 on that sideof the plane a-b of Figure 2 opposite tothe rivets 2 Zand 23, andadjustably extends therethrough, parallel to the shaft 4, to bearagainst the hub portion 2 of the impeller blade.

The screw 28 provides for the required delicate adjustment of the pitchof the impeller blade. As shown in Figure 5, it may be screwed throughthe hub 3 to bend the hub portion 2 away from the hub 3 and therebyadjust the pitch of the blade.

A spring 30 is provided as a backing for the hub portion of the impellerblade. As shown, the spring 30 is secured to the hub 3 by the rivets 22and 23 with the hub portion 2 of the impeller blade therebetween. Itserves to resiliently oppose bending deflection of the hub portion ofthe impeller blade, to hold it against the screw 28, and to return it toits original ilat position against the face of the hub 3 upon retractionof the screw 28, in the event that the material of the hub portion ofthe impeller blade is insuiciently springy to assure this.

I claim:

1. In a device driven by fluid ow, a shaft, an impeller blade with abendable hub portion extending substantially normal to the axis of saidshaft on opposite sides of a plane containing the shaft axis and thecenter line of the impeller blade, said hub portion of the impellerblade being attached to the shaft only on one side of said plane along aline parallel to and removed from the center line of the impeller blade,and screw means on the other side of said plane for adjusting the pitchof the impeller blade by bending deflection of its hub portion about itsline of at'- tachment to the shaft.

2. The combination according to claim 1, in which the hub portion of theimpeller blade is secured to a rigid hub on the shaft, the screwadjusting means including a screw in screw threaded engagement with oneof said hubs and adjustably extending therethrough, parallel with saidshaft, to exert a thrust on the other of said hubs, whereby the bendablehub portion of the impeller blade is bent to effect the requiredadjustment of the pitch thereof.

3. The combinationV according to claim 1 in which the hub portion of theimpeller blade is secured to a rigid hub on the shaft, the screwadjusting means including a screw in screw threaded engagement with saidrigid hub and adjustably extending therethrough to exert a thrust on thehub portion of the impeller blade, whereby the latter is bent to eiectthe required adjustment of the pitch thereof.

4. The combination according to claim 1 in which bending deflection ofthe hub portion of the impeller blade by the screw means is opposed byspring means secured to said shaft.

EDWARD V. RIPPINGILLE.

